Rear seat belts with pretensioners

[johnnybravo]

I have a Ph2 172 where the rear seat belts have gone off in an accident (but nothing else)

Do the rear seat belt units come as a complete unit with the PT, or are the PT units available separately?

Also, what other models have rear seat belts with pretentioners? Are there any? and if so, will they work in a 172? (looking at sourcing some S/H rear belts if possible)

Thanks and sorry for the Spanish Inquisition type post...